1. Field of the Invention
The present invention relates to a road surface heating vehicle and a gas supply system therefor.
2. Description of the Prior Art
Conventionally, in the case of remedying an asphalt paved road, a paved surface layer thereof was heated by a road surface heating vehicle to soften the composite asphalt material. Thereafter, the paved surface layer was scarified, an asphalt softening agent was scattered thereon, and the resulting layer was then stirred, levelled and supplemented, as the occasion demands, with a new composite paving material, by using a road surface layer reproducing vehicle. The resulting layer was then rolled by a succeeding rolling vehicle. Thus, the remedying operation was finished.
The prior art road surface heating vehicle which has hitherto been employed for such remedying purpose, generally, is of a gas burning type which is constructed such that heating panels are provided on the underside of a body of the vehicle in such a manner that they are kept at a level spaced by a prescribed distance from the surface of a road involved, the heating panels being supplied with gas from the propane gas cylinders loaded on the body of the vehicle. A number of small-sized cylinders are used as such gas cylinders.
The above-mentioned prior art road surface heating vehicle has the following problems.
(1) Since the propane gas cylinders loaded on the body of the vehicle are small-sized, at the time of filling the propane gas it is necessary to unload the cylinders the interior gas of which has been used up, and instead to load new gas cylinders filled up with the propane gas. This necessitates raising and lowering the propane gas cylinders by means of, for example, a crane, requiring a large amount of time and labour.
While the liquefied gas is charged in the gas cylinders, it deprives its surroundings of their heat when it is vaporized. As a result, the vaporizers are cooled to make the gas difficult to vaporize. This may often result in a failure to cause the heating panels to be kept at a required level of calorie, causing a remarkable decrease in the working efficiency. This tendency is prominent particularly in winter season, or on a land which is a great distance above the sea level.
SUMMARY OF THE INVENTION
The present invention has been made in order to solve the above-mentioned problems and the object thereof is to provide a road surface heating vehicle and a gas supply system therefor which are adapted to supply the gas kept always at a uniform level, to the heating panels, thereby enhancing the working efficiency involved.
To attain the above object, according to one aspect of the present invention, there is provided a road surface heating vehicle which has an automotive body and is equipped, on the underside of the automotive body, with heating panels and, on the automotive body, with a gas tank, the vehicle comprising a plurality of vaporizers disposed on the automotive body, the plurality of vaporizers being connected in parallel to each other by means of a gas line and a liquid line both of which extend from the gas tank. the gas line being made to branch into branch lines, the branch lines being connected to respective burners of the heating panels respectively, each of the liquid line and the gas lines being mounted with a solenoid valve and a pressure adjusting valve, the gas tank being equipped not only with a thermometer and a pressure adjusting valve but also with a heat directing fan at the side thereof, which, when required directs hot exhaust gases from the heating panels toward the gas tank to promote vaporization of the liquefied gas in the tank, the automotive body having disposed thereon an operating board containing therein a microcomputer to which there is connected electric circuits for a control system for said vaporizers, the solenoid valves, the pressure adjusting valves, the thermometer, and a fan motor used to drive the heat directing fan, whereby, when the gaseous pressure in the gas tank has exceeded a specified level, the microcomputer automatically causes a closing of the solenoid valve on the liquid line and at the same time causes a stopping of the fan operation, whereas, when the gaseous pressure has decreased down to a specified level, the microcomputer automatically causes a starting of the fan operation and at the same time causes opening of the solenoid valve on the liquid line so as to cause operation of the vaporizers.
According to another aspect of the present invention, there is provided a gas supply system for the road surface heating vehicle, which comprises a gas tank loaded on the vehicle, a heater provided on a body of the vehicle, a gas line provided between the gas tank and the heater, a plurality of vaporizers connected in parallel to the gas line, a liquid line connected to the plurality of vaporizers, and a microcomputer provided within an operating board provided on the body of the vehicle, the gas line and the liquid line being each mounted with a solenoid valve, the gas tank being provided with a termometer and a gas pressure gauge and also provided, at the outside thereof, with a heat directing fan, which, when required directs hot exhaust gases from the heating panels towards the gas tank to promote vaporization of the liquefied gas in the tank, the microcomputer being connected thereto with electric circuits for the vaporizers, the solenoid valves, the thermometer, the gaseous pressure gauge, and a fan motor, whereby the microcomputer performs its control operation in such a way that when, in operation, the pressure of the gas being supplied is kept at a level of 10 kg/cm.sup.2 or more, or alternatively when the temperature of the gas tank has exceeded a level of 40.degree. C., it automatically causes a closing of the solenoid valve on the liquid line and at the same time a stopping of the fan motor, whereas, when, in operation, the pressure of the gas being supplied has decreased down to a level of 5 /cm.sup.2 or less, the microcomputer automatically causes a rotation of the fan motor and at the same time causes opening of the solenoid valve on the liquid line so as to cause operation of the vaporizers.
By turning a main switch on, each solenoid valve is opened to permit the vaporizer to operate. This permits the gas to be supplied to each heating panel, which gas is then automatically ignited. Whereby, the road surface heating vehicle can heat the surface of the paved road at a specified temperature.
During the above operation, when, in summer season, the liquefied gas is spontaneously vaporized within the gas tank with the result that the gaseous pressure has a level of 10 kg/cm.sup.2 or more or the interior temperature of the gas tank exceeds 40.degree. C., the automatic control system starts to operate. Consequently, the solenoid valve on the liquid line adapted to supply the liquefied gas from the gas tank to the vaporizers is closed and, at the same time, the heat directing fan adapted to promote the vaporization in the gas tank is stopped from operating. When, on the other hand, the gaseous pressure has decreased down to a level of 5 kg/cm.sup.2 or less, the heat directing fan is automatically rotated to cause promotion of the vaporization of the liquefied gas in the gas tank. At the same time, the solenoid valve on the liquid line is opened to permit the vaporization of the liquefied gas in the vaporizers. Further, where in winter season, a plurality of vaporizers are in some cases all caused to make their operations, or in other cases only one of them is operated, whereby the vaporizing operation can automatically be controlled in accordance with the variations in the pressure of the gas so as to cause the gas of uniform pressure to be supplied to the heating panels. That is to say, even when the temperature of the open air varies during the heating operation to promote the vaporization in the gas tank to cause variation in the gaseous pressure, automatic control works to cause such gaseous pressure to be kept at a uniform level.